1. Field of the Invention
The present invention relates to an image processing method and apparatus, an image processing system and a storage medium.
2. Description of the Related Art
Conventionally, there is known an image processing system for generating image data in digital form for printing. Such a system as shown in FIG. 1 is generally used. FIG. 1 is a block diagram of a system for preparing a page layout document, a word processor or graphic document or the like by performing DTP (Desk Top Publishing) by using a host computer 101 to hard-copy output by using a laser beam printer, an ink jet printer or the like.
In FIG. 1, reference numeral 102 denotes an application which operates in a host computer. As representative samples of the application 102, there are such word processor software as Word (R) from Microsoft Corporation and such page layout software as PageMaker(R) from Adobe Corporation. Digital documents prepared by these software products are supplied to a printer driver 103 through an operating system (OS) of a computer (not shown).
The digital document is normally represented as a set of command data representing patterns, characters or the like, which configure one page, and these commands are to be transmitted to the printer driver 103. A series of commands configuring a screen are represented by a language system called PDL (Page Description Language). Representative example, of such PDL are GDI(R), PS(R) (Post-Script) and the like.
The printer driver 103 transfers the received PDL command to a rasterizer 105 within a raster image processor 104. The rasterizer 105 develops characters, patterns or the like expressed by the PDL command into a two-dimensional bitmap image for actually printer-outputting. Since the bitmap image becomes an image that completely fills a two-dimensional plane by repeating one-dimensional raster (line), this element 105 is called a “rasterizer”. The bitmap image thus developed is temporarily stored in an image memory 106.
The foregoing operations are shown in FIG. 2. A document image 111 displayed on the host computer is transmitted to the rasterizer through the printer driver as a PDL command string 112, and the rasterizer develops the two-dimensional bitmap image on an image memory 106 as denoted by 113. The image data thus developed is transmitted to a color printer 107. The color printer 107 is provided with a known image forming unit 108 of the electrophotographic type or the ink jet recording type, which forms a visible image on a sheet for print-outputting. In this respect, the image data in an image memory 106 is transferred in synchronism with a request for transfer by a synchronizing signal, a clock signal or a specific color component signal (not shown) which is necessary to operate the image forming unit 108.